The present invention relates generally to a radio signal transmitter for generating a radio signal indicative of a preset code for operating automotive vehicle devices, such as a door lock mechanism, a trunk lid lock opener and so forth. More specifically, the invention relates to a compact radio signal transmitter equivalent in size to a bankcard, creditcard and the like.
A recently proposed keyless entry system for an automotive vehicle does not require mechanical key operation or manual entry of a preset code for operating a door lock mechanism for locking and unlocking the door, a trunk lid opener for opening the trunk lid, and so forth. In this keyless entry system, a bank- or credit-card-type radio signal transmitter has been employed to generate a radio signal indicative of a preset code. The preset-code-indicative radio signal is sent to a controller mounted on the vehicle which operates the door lock mechanism, the trunk lid opener and so forth when the code in the radio signal coincides with the preset code in the controller.
The radio signal transmitter of this type is adapted to be carried in clothing pockets. A radio signal transmitter carried this way will be subject to bending stresses as the user moves naturally. Since the radio signal transmitter contains a plurality of circuit elements mounted on a relatively flexible circuit board within a small, thin transmitter housing, such bending stresses can easily damage the circuit board itself or the circuit elements on the circuit board.